Burglar-alarm



(No Modpl.) 2 Sheets-Sheet 1.

0. LARSON.

BURGLAR ALARM.

No. 531,955. Patented. Jan. 1, 1895.

(No Model.) 2 Sheets-Sheet 2.

O. LARSON. BURGLAR ALARM.

' No. 531,955. Patented Jan. 1, 1895 W OM 2 UNITED STATES PATENT EEioE,

OLAUS LARSON, OF CHICAGO, ILLINOIS.

BU RGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 531,955, dated January1, 1895. Applicatlen filed July 6, 1894- Serial No. 516,768. (No model.)

To all whom it may concern:

Be it known that I, OLAUS LARSON, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Burglar-Alarms; and I dohereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

My invention relates to an improved burglar alarm, adapted to beattached to a door or look.

The object of theinvcntion is to provide a simply constructed andeflicient apparatus, which may be readily attached to the escutcheonplate orlock of a door in such manner that a key or other instrumentcannot be inserted to unlock the door without causing an alarm bell toring, and thereby to arouse the occupant of the room, and give timelywarning of impending intrusion; and which is also adapted to beelectrically connected to sound an alarm at the same time in other roomsof the building or elsewhere.

The invention consists in the combination and arrangement of parts, thenovel features of which are hereinafter fully described and set forth,reference being had to the accompanying drawings, in which- Figure 1 isa side elevation of my improved burglar alarm shown in an operativeposition attached to the section of a door and lock. Fig. 2 is avertical section of the apparatus taken on the line 2, 2, of Fig. 3, thealarm bell being shown in full lines. Fig. 3 is a view of the insideface with a portion broken out to show the clock gearing within thebell. Fig. 4 is a top view of the apparatus partly cut away.

Referring to the drawing-1. designates the door which as represented isof the ordinary kind provided with the usual escutcheon or key-holeplates 2, and mortise lock 3, into which a key 4 is shown partlyinserted.

5. is the alarm bell within which a clapper 6 is pivotally attached to acrank, and adapted to be rapidly rotated and carried around therewith toring the hell by means of clock gearing operated by a clock spring,adapted to be wound up by the lever key 7, and held by a ratchet wheeland pawl. The construe tion of the bell and gearing by which it is madeto ring is without novelty, being identical with that in general use foralarm clocks, and will be readily understood without further referencethereto. Said bell and appurtenant parts are rigidly secured to a flangedisk 8, to the inside of which an escapement pawl i) is pivotallyattached. The lower end of the pawl is bent and projects through thedisk plate, and is adapted to engage with the bell clapper to stop thebell. Said pawl is made to engage said parts by means of a flat steelspring 10 resting thereon, the outer end of which is rigidly secured toa flat rock arm or pivoted lever 11 in manner resembling a bell crank.Said lever projects outward through the disk-flange, and is for thepurpose of moving the spring from one end of the escapeinent pawl to theopposite end; or, to change or remove the spring pressure from one sideof the pawl supporting pivot to the other side thereof as is shown bydotted lines in Fig. 3. When said springis in the position of the fulllines, the projecting end of the pawl is pressed to engage with theclapper and stops the bell; but, when the spring press ure istransferred to the opposite side of the pivot, the pawl will be liftedto ring the bell, unless an opposing pressure intervenes to preventitand such is the case. The act of attaching the apparatus to a doorcarries forward an opposing or counteracting spring of slightly greaterpower than that exerted by the flat spring, which is turnedto theposition of the dotted lines after the apparatus is attached, so thatthe flat spring must be aided when the apparatus is set in order to liftthe pawl and start the alarm; the object and manner of doing, which willbe made apparent farther on.

12. is a head-stock or frame, the bottom of which is curved to fit thedisk-flange, and is rigidly secured thereto. Said frame bottom has earformed portions 13 which are turned downward, and pass throughperforations in the disk-flange. Said ears are perforated for theinsertion of the curved distance wire it, which is adapted to be sprungtherein, and to be turned up against the door for the lateral support ofthe apparatus.

15. is acylindrical steel tube fitted into perforations in the uprightsof said head-stock frame, and is rigidly held therein. One end of saidtube projects outward therefrom, and

' is provided with a plurality of integrally formed branches or fingers16, which are closed together at their ends, and reduced in diameter tonormally admit the insertion therein of the key-push-rod l7, and for theinsertion of said finger ends into the smallest key-hole forwhich theapparatus is designed. Said fingers are spring tempered, and haveoutward projecting ends adapted to hook behind the escutcheon plate, orto be forced into the wood if the door is without a plate.

18. is an inner tube adapted to be moved forward longitudinally withinthe finger-tube to expand said fingers, and secure the apparatus to thedoor, and to be moved backward therein to permit the resilient closingof the fingers for the detachment of the. apparatus therefrom. Saidinner tube has a disk 19 attached to its outer end by which it is movedand adjusted, and is provided with a pin 20, rigidly secured thereto.Said pin projects through a slotted opening 21 in the top of the fingertube; the slot having notches 22 formed upon one side thereof, intowhich said pin is adapted to be turned to form a lock and prevent theinner tube from being pushed back by the finger pressure thereon, orfrom possible pressure applied through the key-hole.

23. is a cylindrical plug fitted to the inner tube, and adapted to slidetherein. Said plug has a central bore, into which the key-push rod 17 isinserted and adapted to be adjusted to stand out such distance as isrequired by the thickness of the door, and to be rigidly secured to saidplug when adjusted by means of a set screw 24 in the plug, and a seriesof circumferential grooves 25 formed upon the push-rod, by whicharrangement, though it were possible to turn or revolve the push-rodfrom the outside, it cannot be twisted off and removed to make room forthe key. Said cylindrical plug is provided with a downward projectingpin 26, which passes through a slotted opening 27 in the inner tube, andalso through a like slot 28 in the finger tube; the inner tube slotbeing cut wider to permit the turning the tube when it is to be locked.

29. is a spiral springinterposed between the end of the cylindrical plugand disk end of the inner tube, the spring being held slightlycompressed therein by the pin in the plug resting against the end of theslot in the inner tube. It will now be seen that in attaching theapparatus to the door, the pin in the plug will be carried forward bythe movement of the inner tube which at the same time expands thefingers, until it is brought to bear against the upper end of theescapement pawl (see Fig. 1) upon the opposite of which the flat springis now turned to act, and as the force of the spiral spring is greatestthe flat spring cannot act to lift the pawl to ring the alarm until itsforce is made predominant, or greater than the opposing spiral spring,and thisoccurs the moment the push-rod is pressed back,

and the pressure of the spiral spring upon the pawl is either lessenedor removed therefrom by the insertion of a key or otherinstrument; thearrangement producing a positive and sensitive action, requiring but aslight pressure upon the push-rod to ring the bell.

30. is a flat metal plate secured to the headstock frame to form asupport for the hand or fingers in pushing the inner tube to attach theapparatus.

The operation consists in attaching the apparatus to the doorasdescribed, adjusting the push-rod to the desired point in the lock, andturning the flat spring to press upon the upper end of the escapementpawl.

It will be observed that thepush-rod may be extended out into the lookfar enough to prevent the full insertion of the key, or it may bewithdrawn to a point that will admit of its being pushed back sufficientfor the key to be operated-to unlock the door, and that by thisarrangement the occupant of a room may leave his room door locked withthe alarm attached thereto, so that persons in other parts of the housewould be notified, should entrance be made other than at the usualhour-of departure and return.

The invention'is' one of great utility and efficiency, and in itsadaptation and convenience of attachment to "and removal from a door,forms a desirable alarm appliance; and is. especially useful as anadjunct to a travelers outfit, its size being such that it may beconveniently carried about the person or in a hand-bag.

The apparatus is constructed chiefly of brass,but may beof any suitablematerial, and plated or finished in any desirable manner.

, I am aware thatitis not a new per se to ring an alarm hell, bymechanical means, and I make no claim to such as my invention.

In my invention the alarm apparatus is adapted to be readily attachedtoa door or look by means of the key-hole therein, and so sensitizedthat any tampering with the lock instantlysets the alarm bell ringing.

Having thus fully described my invention, I claim- 1. In an alarmapparatus adapted to be operated by the insertion of a key or otherinstrument into the lock of a door the combination therewith of thedescribed spring formed expansible fingers, adapted to be attached tosaid apparatus, and to be inserted into the key-hole or lock of a door,and means adapted to expand said fingers in said keyhole to secure saidalarm apparatus to said tobe inserted in the key-hole of a door or lock,

and to be expanded therein to secure said apparatus to said door; andakey-push-rod-held centrally between said fingers, and adapted to bepushed back by the insertion of a key into said lock and door to liftsaid escapement pawl, and thereby to cause said alarm bell to ringsubstantially as and for the purpose specified.

3. In the described burglar alarm apparatus, the combination of thefingers adapted to be expanded within the key-hole of a door to securesaid apparatus thereto; a push-rod extending into said key-hole, andheld centrally therein between said fingers, a pivoted escapement pawl,adapted to be lifted by the movement of said push-rod, to allow thealarm bell of said apparatus to ring and a spring acting against saidpawl, and adapted to be moved thereon to transfer the pressure of saidspring to either side of said pawl pivot substantially as and for thepurpose specified.

i. The combination in the described alarm apparatus of a fixedcylindrical tube provided with integrally formed fingers, adapted to beinserted into the key-hole of a door; an inner tube inserted within saidfixed or finger tube, and adapted to be moved therein to expand saidfingers in said door key-hole, to secure said apparatus thereto, and tobe turned and locked therein against being moved back in said fingertube when said fingers are expanded; a cylindrical plug inserted withinsaid inner tube; a key-push-rod inserted in said cylindrical block, andlongitudinally adjustable therein as described, a spring inserted intosaid inner tube, adapted to act against the end of said cylindricalplug, and an escapementpawl, adapted to be held in a locked ornon-escapement position by means of said spring, substantially as andfor the purpose specified.

5. The combination in the described burglar alarm apparatus comprising abell, clock gearing, adapted to be wound up to ring said bell; a pivotedescapement pawl to control the ringing of said bell; said bell and partsattached to a circular flanged disk, a spring adapted to be moved toeither end of said pawl, or upon either side of its pivot connection bymeans of a lever attached thereto; a pivotally attached distance orsupporting rod, adapted to be turned down within said flanged disk, ahead-stock frame attached to said flanged disk, a tube rigidly attachedto said head-stock; said tube provided with integrally formed expansiblefingers, adapted to be inserted into the key-hole of a door or look, amovable inner tube, adapted to expand said fingers to secure saidapparatus to a door, a cylindrical plug within said inner tube, provided with an adjustable key-push-rod, and a spring within said innertube, adapted to press against the end of said plug, and also to bebrought to bear against said escapement pawl, combined and arranged inthe manner and for the purpose substantially as specified.

In testimony whereof I affix my signature in presence of two witnesses.

OLAUS LARSON.

YVitnesses:

EDWARD S. CURTIS, OLNEY B. STUART.

